Researchers at Cornell University have found that fewer nutrients are lost when food is cooked in microwave ovens. In the case of fruits and vegetables, for example, up to 50 percent less vitamin C is lost when food is cooked this way. During regular cooking, nutrients are lost to the cooking water. But microwave cooking uses the water that is already in the food. Microwaves cook food by causing water molecules in food to vibrate. The vibrating gives off heat. Microwave cooking is even more efficient when the food is placed in the microwave oven in a paper container. Since less time is needed (up to 70 percent less time) for cooking, there is less heat damage to nutrients. The researchers found that there is less damage to the protein in flour based foods because of the shorter cooking time. There has been some concern in the past that microwave radiation leaking from microwave ovens could do harm to us. However, the researchers say that these ovens do not pose a danger to humans. Microwaves cook food by .